in HEP the infrared radiation in the sun's rays causes the water in lakes , rivcers etc. to evapourate , this water vapour :

climbs in height and eventually condenses and falls as rain on high ground . this is collected behinds dams and electrical energy is created as the water falls back via turbines

what are the advantages of HEP

hydroelectric schemes dont cause pollution

hydroelectric schemes are generally very reliable

they can also be started up very quickly to meet sudden increases in the demand for electricity

what are the disadvanatges of HEP

few areas of the worl are very suitable

they alter the landscape , and they upset the balance of local plant life by the destruction of wildlife habitats

hydroelectric schemes involve damming upland river valleys , this means flodding land that may have been previously used for farming or forestry

HEP - water in the resevoir is at a high level and has ..... ..... energy . As the water falls to a lower level this energy is converted into ..... energy of the flowing water . As the water flows through the turbine it slows down losing its kinetic energy which is converted into the ...... energy , this time of the turbine which rotates . The generator converts the .... energy of the turbine into ..... energy which can be transmitted to the consumer

they aren't really a means of generating electrical power . they're a way of storing energy so that we can release it quickly when we need it .

demand for electrical power changes throughout the day for example , when a popular TV programme finishes , a huge number of people go out and put the kettle on causing a sudden peak in demand . this is called a :

TV pickup

following a TV pickup , if power station sdont generate more power immediately , there'll be :

power cuts all around the country - traffic lights will go out , causing accidents , and all sorts of other trouble will occur .

following a TV pickup , if power station sdont generate more power immediately , there'll be power cuts all around the country - traffic lights will go out , causing accidents , and all sorts of other trouble will occur . the problem is most of power is generated by fossil fuel power stations , which :

take half an hour or so to crank themselves up to full power . Nuclear power stations take even longer . we need something that can go from nothing to full power immediately , and keep us supplied for around half an hour until the other power stations catch up . this is where pumped stroage systems come in

describe the process of a pumped storage system

water is pumped up to the top reservoir at night , when demand across the country is low .

When thers's a sudden demand for power , the "headgates" (huge taps) are opened , and water rushes down the tunnels to drive the turbines , which drive powerful generators

the water then collects in the bottom reservoir , ready to be pumped back up later

pumped storage uses the same idea as :

HEP but it isnt a way of generating electricity - its simply a way of storing energy which has already been generated